I dont recall DB/DR ever mention about NOT gathering intel so as to expose the affair. Once you have confronted and gotten the affair out in the open, then the snooping should stop for your own sanity.

Here is a great article (that mentions MWD) that I think speaks well for the advice that PuppyDogTails gives...

http://symcinc.com/getinformed/articles/endingaffair.html

I dont think the advice Puppy gives is anti-DB at all.

MWD has one chapter on infidelity which is good. But should we only be rigid and accept that as the only guidance? I found Glass's "Not Just Friends" to have much more detail concerning affairs. And Dobson's advice is good too.